1. Field of the Invention
The present invention relates to a zone temperature control structure having zone of which surface temperatures are controlled to different temperature, respectively.
2. Description of the Related Art
As a mounting stage (susceptor) on which a wafer is mounted in a substrate processing apparatus that subjects a semiconductor wafer (hereafter referred to merely as “the wafer”) as a substrate to plasma processing, there is known a susceptor that controls a mounting surface divided into a plurality of temperature zones and supports a wafer in the temperature zones.
A zone temperature control structure of which surface is controlled to a plurality of temperature zones, or an assembly structure having a plurality of temperature zone assembly members adjusted to different temperatures from one another like the susceptor supporting a wafer in the temperature zones has a problem that when the respective zones are adjusted in temperature, heat transfer occurs on a boundary surface or a connecting surface between different temperature zones adjacent to each other, resulting in decreasing heat efficiency. There is also another problem that a temperature difference between the zones cannot be ensured.
Accordingly, there has been developed a technique that in such a zone temperature control structure or an assembly structure, a heat insulator is disposed between adjacent zones, or adjacent zones are made of materials with different heat conductivities so as to prevent decrease in heat efficiency and ensure a temperature difference between the zones at the time of temperature adjustment (see Japanese Laid-Open Patent Publication No. (Kokai) 2004-292297, for example).
However, when a heat insulator is disposed between the zones controlled to different temperatures in the zone temperature control structure, this raises the problem that in response to heat input in a direction intersecting a direction in which the zones are arrayed, the temperature immediately above the insulator becomes higher than ambient temperature to form a singular point in terms of temperature (hereafter referred to as “the hot spot”). The hot spot does not only hinder temperature uniformity in the zone adjusted/controlled to a predetermined temperature, but also causes heat efficiency to decrease.